自平衡桩基测试双荷载箱技术的工程应用

Engineering application of self-balanced pile loading test using double load cells technique

自平衡试桩法是通过埋置于桩身中的荷载箱施加荷载的一种新型静载试验方法。双荷载箱技术即根据不同的设计要求,将两个荷载箱埋置于桩身特定位置,按照不同的加载次序,分别测出指定桩段的极限承载力,可方便地确定有效桩长的实际承载力、桩压浆前后的承载力、带扩大头桩的承载力、基桩无侧限抗压强度等。工程应用实例表明,双荷载箱技术克服了单荷载箱测试中因平衡点确定不准确而导致所测承载力偏低的问题,依据设计要求和桩周土层性质,灵活组合加载次序可巧妙解决部分传统试桩难以解决的问题。

Self-balanced loading test is a static load test method, in which load cell is embedded in the pile exerts load. Double load cell technique refers to meeting different designing needs. Two load cells are embedded in the specific position of the pile, and ultimate bearing capacity of specified pile is tested according to different loading sequence in order to efficiently determine the actual bearing capacity of efficient pile length, bearing capacity before and after grouting, bearing capacity of pile with expansion head, pile unconfined compressive strength and so forth. Examples of specific engineering practice indicate that the double load cells technique solves the problem that the middle balance point of single load cell is hard to be determined which lead to a lower measured bearing capacity of pile. According to the design requirements and soil layer property around pile, the double load cells can be loaded optionally and solve the problems in the tradition pile test.